1. Copyright Notice
This patent document contains information subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent, as it appears in the U.S. Patent and Trademark Office files or records but otherwise reserves all copyright rights whatsoever.
2. Field of the Invention
The present invention, in certain respects, relates to enterprise storage systems and backup and recovery processes. In other respects, the present invention relates to restoring data from a backup storage device and to reversing a restore of data from a backup storage device to a primary disk.
3. Description of Background Information
Enterprise Storage Systems are utilized to store data for enterprise level applications, and thus play a critical role in many business environments. For example, a company may use an enterprise storage system to migrate its disparate and separately located data centers to a new central location. As another example, an enterprise storage system can facilitate the creation of an infrastructure to allow an internet service provider (ISP) to store, manage, and deliver rich media content, to accommodate backup and restore operations in the event of site failures or disasters, and to allow the ISP to streamline its management of hardware and software platforms and applications.
The data used by such business environments is mission-critical, and thus must be readily and continuously accessible by a host system. Such mission-critical data needs to be protected and continuously available even when a disk fails. A mirror disk (or volume) provides redundancy for a primary disk (or volume). Such mirroring occurs with a standard RAID configuration. Another mirror may be provided for data protection in addition to or instead of a standard RAID type mirror. Such a mirror may alternatively be provided in a Symmetrix(trademark) storage unit along with the primary disk. In this case, the mirror is referred to as a business continuance volume (BCV). Such a mirror may be on one Symmetrix(trademark) connected by a high speed data link to another Symmetrix(trademark) that holds the primary disk. In this case, the mirror is called a Symmetrix Remote Data Facility (SRDF)(trademark) volume. A volume is a storage entity that might correspond to a portion of a hard disk or a group of hard disks within a given enterprise storage platform such as the Symmetrix(trademark) storage platform.
Enterprise storage systems such as those described above perform data backup processes and restore processes. Disk level backups and restores involve the backing up or the restoring of a raw xe2x80x9cimagexe2x80x9d of the entire disk, while file-level backups and restores require file mapping, a process by which data that is located at various physical locations on a disk is converted to data logical order before it is sent to the backup storage devices. In other words, all pieces of a given file are put in their proper contiguous form for storage on the backup storage device (typically, one or more tape drives within a tape library unit). In addition, a file level restore requires a xe2x80x9cpre-allocationxe2x80x9d step in which a file of the correct size, but with null data, is created to provide a destination which may be mapped for restore.
Data may be restored from a backup storage device with mirroring (a mirrored restore). With a mirrored restore, data is typically first read from the backup storage device and stored onto a mirror disk and later moved from the mirror disk to the primary disk for use by the host system.
The present invention is provided, generally, to improve upon disk restore and backup processes, and, more specifically, to provide added flexibility and benefits when performing mirrored disk restores, including both disk level mirrored restores and file level mirrored restores. Rather than first restore data to a mirror disk and later move that data to the primary disk, the data on the primary disk is first copied to the mirror disk, and thereafter, the data is restored from the backup storage device to the primary disk, independent of the mirror disk.
This approach provides a copy of the destination location, as it existed prior to the restore operation. There are situations in which the user may want to reverse the effects of the restore, and bring the system back to the xe2x80x9cpre-restorexe2x80x9d state. One such situation exists when the user decides the restored data is less useful than the data present before the restore. Another such situation exists when a restore is unable to be completed (because, for example, a tape is damaged), in which case the restore system should leave the production system in the same state as that which existed prior to initiating the restore operation.
Other features, objects, and advantages of the present invention may be provided in addition to or instead of the above exemplary description of the invention, and such different aspects of the invention can be gleaned from other portions of the description herein.